Microwave fixation provides excellent preservation of tissue, cells and antigens for light and electron microscopy

Abstract

It was demonstrated that microwave energy used simultaneously in combination with low concentrations of glutaraldehyde (0.05%) and formaldehyde (2.0%) rapidly preserved light microscopic histology and excellent fine structural details, as well as a variety of cytoplasmic and membrane-bound antigens. Specimen blocks up to 1 cm3 can be fixed in as brief a time as 26 ms using a specially designed microwave device (ultrafast microwave fixation method). The fast microwave fixation method, using a commercially available device, was successfully used to preserve granule-bound rat mast cell chymase which was subsequently detected by a postembedding immunogold procedure. Control of the following parameters is important to the microwave fixation method: (1) specimens with one dimension less than 1 cm; (2) irradiation temperatures lower than 50 degrees C; (3) irradiation times less than 50 s; (4) immediate replacement of the postirradiation solution with cold storage buffer; (5) fixing the specimen within 15 min after it is removed from its blood supply.

New tissue fixation method for cytochemistry using migrowave irradiation. I. General remarks.

“…Early studies on this method mentioned temperatures of 50 to 80°C (13,37,38,52,57,58), and then later, 32-42°C (57,61,63). We found that if the temperature of the sample and fixative rise to 40 to 45°C, the membraneous ultrastructures will be broken under high resolution electron microscopy.…”

“…Another unanswered question about the functioning of MWI was why the aldehyde could penetrate instantaneously deep into the tissue block (6,7,37,40,52,53,(57)(58)(59)(60)(61)(62)(63)73). To try to find the solution to these problems and questions, we used 3H-formaldehyde as a tracer in MWI (73 , 76, 34).…”

Improved method for post-embedding cytochemistry using reduced osmium and LR white resin.

“…Although microwave irradiation has recently become widely used and its positive effect in cytochemistry has been confirmed (14,27), the mechanisms of tissue fixation and reactivity preservation by irradiation have yet to be clarified. One possibility is that rapid penetration of mild fixative by microwave irradiation may preserve substances at their original locations that would otherwise diffuse out (14).…”

Application of microwave irradiation in surgical pathology; Improvement of microscopic-image of cryostat sections and exploration in rapid metallic stainings.

“…Microwave irradiation accelerates fixation (3) and staining reactions (5,6,(13)(14)(15)(16). More rapid and accurate routine diagnostic surgical pathology can be expected with microwave irradiation, but with a domestic oven the results seem to be as yet unpredictable (4,16).…”

“…More rapid and accurate routine diagnostic surgical pathology can be expected with microwave irradiation, but with a domestic oven the results seem to be as yet unpredictable (4,16). To obtain reproducible results we need further exploration.…”